DESCRIPTION: (Adapted from application's description) Male infertility is a common problem among couples desiring children. Although it can be caused by many factors, genetics plays a significant role. The formation of mature sperm requires the coordinate expression of many genes. The investigator's long-term objective is to understand this process in order to develop effective treatment. They will focus their studies on two recently isolated spermatogenesis genes, DAZ and DAZLA. DAZ (Deleted in AZoospermia) is a gene family with four or more members, clustering on the long arm of the human Y chromosome. The gene cluster is deleted in about 10% of males-with idiopathic azoospermia or oligospermia. DAZLA (DAZ Like Autosomal) is a gene on chromosome 3 and is highly similar to DAZ. Both DAZ and DAZLA are expressed in germ cells only, and their role in spermatogenesis is shown by their homology to a Drosophila male infertility gene boule. Male mice lacking DAZLA are sterile. Under-standing the functions of these two very similar genes may provide a new strategy to treat male infertility due to DAZ deletion. However, new reagents are needed for functional studies. Two specific aims to prepare these key reagents are therefore proposed. In the first aim, antisera against DAZ and DAZLA proteins will be generated by immunizing rabbits with recombinant proteins produced in E. coli. The antisera will enable the investigators to determine the cellular location of the proteins, and to trace the proteins during subsequent isolation and biochemical studies. In the second aim, proteins that interact with DAZ and DAZLA will be isolated using the yeast two-hybrid system. These interacting proteins may provide clues to the functions of DAZ and DAZLA. They will also serve as reagents for functional analysis and comparison of the two proteins.